Method and apparatus for bending an elongated object

ABSTRACT

Method and apparatus for bending an elongated object. The method comprises gripping at least two portions of the object with rigid instrumentalities, which are spaced apart by a predetermined distance, and then tilting the instrumentalities simultaneously in opposite directions to a calculated extent. The apparatus includes at least two clamping devices for retaining respectively different portions of the object. The clamping devices have base portions which are connected together by means having an extensible portion. Means are provided for lengthening the extensible portions and for thereby forcibly increasing the spacing between the base portions.

United States Patent n 1 Kindermann et al.

[ 51 May 8,1973

[54] METHOD AND APPARATUS FOR BENDING AN ELONGATED OBJECT [73] Assignee: Bell Telephone Laboratories, Incorporated, Murray Hill, NJ.

[22] Filed: July 8, 1971 [21] App]. No.: 160,782

3,335,588 8/1967 Cummings ..72/388 2,316,049 4/1943 Connor 3,396,565 8/1968 Miller 3,568,493 3/1971 Wirt et a].

2,525,403 10/1950 Dewitt ..72/309 Primary Examiner--Charles W. Lanham Assistant Examiner-M. J. Keenan Attorney-R. J. Guenther et a].

[57] ABSTRACT Method and apparatus for bending an elongated object. The method comprises gripping at least two portions of the object with rigid instrumentalities, which are spaced apart by a predetermined distance, and then tilting the instrumentalities simultaneously in opposite directions to a calculated extent. The apparatus includes at least two clamping devices for retaining respectively different portions of the object. The clamping devices have base portions which are connected together by means having an extensible portion. Means are provided for lengthening the extensible portions and for thereby forcibly increasing the spacing between the base portions.

3 Claims, 10 Drawing Figures Patented May 8, 1973 6 Sheets-Sheet 2 FIG. 2

7 3 5 I n w W n D Patented May 8, 1973 3,731,513

6 Sheets-Sheet 5 FIG. .5

Patented May 8, 1973 3,731,513

6 Sheets-Sheet 4 Patented May 8, 1973 6 Sheets-Sheet 5 mm E mm rm 3 Q Q 2 5 mi mm E" 52.6

@m E u 6i 1 METHOD AND APPARATUS FOR BENDING AN ELONGATED OBJECT BACKGROUND OF THE INVENTION This invention relates to a method and apparatus for bending an elongated object and, more particularly, to an improved method and apparatus for making precise bends in sections of rigid circular waveguide.

In many commercial enterprises, there are occasions when it is necessary to effectuate precisely calculated bends in various types of elongated objects. An example of the need for a method and apparatus for making such bends will now be described with reference to microwave radio relay communication systems. As is well known to those skilled in the art, a microwave radio relay communication system employs a number of horn antennas which are individually mounted on the tops of tower structures for the purpose of transmitting and receiving microwave signaling energy. Each antenna is provided with a waveguide connection to microwave networks which constitute portions of transmitting and receiving equipment that is located at the base of the respectively associated tower structure.

Each of these waveguide connections includes a straight section of rigid circular waveguide which is located on the tower structure and extends upward from the respectively associated transmitting and receiving equipment to within about 8 feet of the respectively associated antenna. The remaining portion of each of these waveguide connections has heretofore been constituted by a section of flexible waveguide. This type of waveguide is fabricated with circumferential corrugations formed at spaced intervals along its length so that it can be readily bent to accommodate misalignment produced by offset positioning and tilting of the respectively associated horn antenna.

Although these sections of flexible waveguide are useful in quickly and easily completing the waveguide connections between the antennas and their respectively associated microwave networks, it has been discovered that the corrugated inner surfaces of these flexible waveguide sections produce impedance discontinuities whichcause unwanted modes of transmission of the microwave signaling energy thereby resulting in echoes, intermodulation noise, and delay distortion of the signals. Accordingly, it has'been determined that the quality and reliability of the signals can be improved by replacing the flexible waveguide sections with sections of smooth-bore rigid circular waveguide which has been properly bent for the purpose of accommodating the above-mentioned misalignment.

In most instances, the accommodation of the tilt and offset misalignments can only be made by bending the substitutedrigid waveguide in two places in a single plane. These two bends in each section of the substituted rigid waveguide should be as large and nearly sectional shape of the waveguide because any distortions thereof would produce undesirable impedance discontinuities which, in turn, would impair the quality of communication signals transmitted along the waveguide.

SUMMARY OF THE INVENTION The present invention is designed to provide a method and apparatus for making precise bends, especially low-angle bends, in an elongated object, such as in a section of the above-mentioned rigid circular waveguide. The method comprises gripping at least two portions of the elongated object with rigid instrumentalities, which are spaced apart by a predetermined distance, and then tilting the instrumentalities simultaneously in opposite directions to a calculated extent.

The bending apparatus is basically a hydraulically operated mechanism and includes two clamping devices which are adapted to be securely fastened to respectively different portions of the object that is to be bent so that it is firmly retained thereby. Another portion of the object that is to be bent is adapted to be mounted on a hydraulically operated supporting device. The clamping devices have downwardly extending body portions which are normally disposed in parallel to each other. Each of these body portions is equipped at its lower end with a base portion. The two base portions are connected together by means having an extensible portion. Hydraulically operated means are provided for lengthening this extensible portion and for thereby forcibly increasing the spacing between the two base portions.

When the two base portions are thus forced further apart, the body portions will cease to be parallel to each other and the clamping devices will be forced to tilt simultaneously in opposite directions. This oppositely directed tilting action causes the retained elongated object to be bent so that a curve is established in that portion of its longitudinal axis which extends between the two clamping devices. The degree of curvature of this bend is measured by means including an inclinometer, which is fixedly attached to the body portion of one of the clamping devices, and a spirit level, which is fastened to the body portion of the other clamping device. Thus, a unique principle of operation of this bending apparatus is that it does not require any physical datum or reference surface from which the degree of bending is measured but, instead, uses gravity as the reference datum.

BRIEF DESCRIPTION OF THE DRAWING The features of this invention are more fully discussed hereafter in connection with the following detailed description ofthe drawing in which:

FIG. 1 is a perspective view of apparatus constructed in accordance with this invention for making precise bends in a section of rigid circular waveguide;

FIG. 2 is an elevational plan view of the bending apparatus taken along the line 2-2 of FIG. 1;

FIG. 3 is an end view of the bending apparatus taken along the line 3--3 in FIG. 2;

FIG. 4 is a side view of the bending apparatus of FIG. 1 and showing a straight section of rigid circular waveguide retained therein preparatory to being bent;

'FIG. is another side view of the bending apparatus of FIG. 1 but showing it in its condition after making a bend in the section of waveguide;

FIG. 6 is still another side view of the bending apparatus of FIG. 1 but showing the left end of the waveguide elevated for the purpose of measuring the bend made in the waveguide;

FIG. 7 is a side view somewhat similar to FIG. 4 but showing the bending apparatus holding a bent section of waveguide in preparation for the formation of a second bend therein;

FIG. 8 is a side view somewhat similar to FIG. 5 but showing the bending apparatus in its condition after making a second bend in the section of waveguide;

FIG. 9 is a side view somewhat similar to FIG. 6 but showing the left end of the waveguide elevated for the purpose of measuring the offset between its ends; and

FIG. is a schematic diagram of the hydraulic pressure system and showing its valves, hose lines, and fittings.

DETAILED DESCRIPTION The invention will now be described with reference to a specific exemplary embodiment thereof; namely, a bending machine for making precise bends in sections of rigid circular waveguide. In the drawing, the machine is represented as comprising two clamping devices constituted by a left bending head 1 and a right bending head 2. The heads 1 and 2 are made ofa suitable material, such as cast aluminum. As can be seen in FIG. 1, the right bending head 2 is made in two parts including a lower clamping portion 3 and an upper clamping portion 4 which is hinged to the lower portion 3by any appropriate means so that it can be swung upward as is represented in FIG. 1. The interior mating surfaces of the clamping portions 3 and 4 are formed in the manner of a trough for surrounding an end portion of a section of rigid circular waveguide 5. The left bending head 1 is similarly constructed with a lower portion 6 and an upper portion 7. This left bending head 1 is illustrated in FIG. 1 with its two clamping portions 6 and 7 closed around a different portion of the waveguide 5. The raised position of its upper clamping portion 7 is shown in phantom in FIG. 1.

Each of the lower clamping portions 3 and 6 has two bolts 8 pivotally attached thereto in any convenient manner. Normally, the bolts 8 hang downward as is represented in FIG. 1 by the bolts 8 on the right head 2. Also, both the upper clamping portions 4 and 7 are normally swung upward to their raised positions. This enables the waveguide section 5 to be laid in the trough areas ofthe lower clamping portions 3 and 6. When this has been done, the upper clamping portions 4 and 7 are swung downward to engage portions of the upper surface of the waveguide 5. It should be noted that the trough areas of the clamping portions 3, 4, 6, and 7 each has a semicylindrical shape, as is best represented by the trough area 9, and are so proportioned as to fit snugly around the waveguide 5. After the upper clamping portions 4 and 7 have been swung downward, the bolts 8 are swung upward into slots 10 formed in the edges of the upper portions 4 and 7. Nuts 11, which are carried on the bolts 8, are then tightened, as is represented by the nuts 11 on the left bending head I.

This serves to fasten, or attach, the two bending heads l and 2 to the waveguide 5 so that it is firmly held and retained by them.

As is shown in FIG. 1, the left bending head 1 has a body portion constituted by two downwardly extending legs 12 and 13 which are parallel to each other. The front leg 12 has a bracket 14 to which is attached a conventional inclinorneter 15 comprising a spirit level 16 and a rotatable micrometer head 17. As is well known to those skilled in the art, when the micrometer head 17 is rotated, it effects the tilting of one end of the spirit level 16 and the number of degrees in the tilt angle can be interpreted directly from the markings on the micrometer head 17. The body portion of the left bending head 1 further comprises a base portion constituted by the lower portions of the legs 12 and 13 and which, for convenience, is designated in the drawing as B1.

The right bending head 2 is formed with a body portion having two downwardly extending legs 18 and 19 which are parallel to each other. The front leg 18 is provided with a bracket having a conventional spirit level 21 fixedly attached thereto. The body portion of this right bending head 2 also comprises a base portion that is constituted by the lower portions of the legs 18 and 19 and which, for convenience, is designated in the drawing as B2.

The left and right base portions B1 and B2 of the bending heads 1 and 2 are normally positioned between two rails 22 which are parallelly disposed on the top 23 of a bench or similar object and which are securely fastened thereto by any convenient means, such as by screws. The right base portion B2 is rotatably attached to a section of the rails 22 by suitable pivot means which, in this specific embodiment of the invention, is constituted by a pivot rod 24. It should be noted that the base portion B2 does not rest on the bench top 23 but, instead, is supported by the pivot rod 24 a sufficient distance above the bench top 23 so that the base portion B2 and its bending head 2 can rotate about the pivot rod 24 for tilting downward to the positions shown in FIGS. 5 and 8.

The two base portions B1 and B2 are connected together by means having an extensible portion. These means include a double-acting hydraulic cylinder 25 which is horizontally disposed in parallel to the intermediate portion of the waveguide 5 which is held between the two bending heads 1 and 2. The extensible portion comprises a piston 26 which is adapted to slide in'and out of the cylinder 25 in response to hydraulic pressure as is explained hereinafter. It is sufficient at this point to state that, when hydraulic pressure forces the piston 26 out of the cylinder 25, the extensible portion constituted by the piston 26 is lengthened thereby forcibly increasing the spacing between the two base portions B1 and B2. This results from the fact that the left base portion B1 is fastened to the cylinder 25 and the right base portion B2 is attached to the piston 26 as will now be explained.

The manner in which the right base portion B2 is attached to the piston 26 can be best understood by referring to FIG. 2 where it can be seen that the right end of the piston 26 is provided with a clevis or hub 27 which holds the middle portion of a trunnion 28. The ends of the trunnion 28 extend through holes in the legs 18 and 19 of the right base portion B2 thus serving to couple or fasten the base portion B2 to the right end of the piston 26. The holes in the legs 18 and 19 are slightly larger than the trunnion 28 so that the right base portion B2 can rotate thereon when it tilts downward to the positions shown in FIGS. 5 and 8.

The left base portion B1 is attached to the cylinder 25 by means that are best illustrated in FIGS. 2 and 3 wherein it can be seen that the cylinder 25 is encircled by a housing or collar 29 having two trunnions 31 projecting from its opposite sides. Each of the trunnions 31 extends and protrudes through a hole in a respectively associated rectangular plate 32. These holes in the plates 32 are slightly larger than the trunnions 31 so that the trunnions 31 can rotate freely therein.

The lower sides of the legs'l2 and 13 are provided with slots 33 so that the left base portion B1 can be passed downward over the protruding ends of the trunnions 31. After this has been done, the legs 12 and 13 are fastened to their respectively associated plates 32 by any suitable means, such as by screws. Thus, the left base portion B1 is securely attached to the trunnions 31. Since the trunnions 31 can rotate freely in the holes in the plates 32, this action allows the left base portion B1 to tilt downward into the positions shown in FIGS. 5 and 8.

.The collar 29 is held at a selected position upon the cylinder 25 by means which include a left end cap 34 that is securely fastened to the left end of the cylinder 25 in any convenient manner. Four threaded rods 35 pass through the corners of the end cap 34 and'extend into the left side of the collar 29. A right end cap 36 is securely attached to the right end of the cylinder 25 in any suitable manner. This end cap 36 isso designed as not to interfere with the sliding movement of the piston 26 through the right end of the cylinder 25. Four threaded rods 37 pass through the corners of the right end cap 36 and extend into the right side of the collar 29. It can be understood by those skilled in the art that the collar 29 can be placed at any desired position upon the cylinder 25 .by properly adjusting the effective lengths of the two groups of threaded rods 35 and 37. Thus, by means of the collar 29 and its associated elements, the left base portion B1 is attached, or coupled, to the cylinder 25.

The sliding movement of the piston 26 is effected by the pressure of fluid in the double-acting hydraulic cylinder 25 and this pressure is produced by means ofa conventional manually operated hydraulic pump 38 having a pump handle 39 and a release valve 41, as is best seen in FIG. 1. The pump 38 is provided with a pressure hose line 42 which conducts the fluid, such as oil, from the pump 38 to two bidirectional control valves 65 and 68 that are mounted beneath the bench top 23. The operation of the valves 65 and 68 is controlled by two handles 44 and 45 which are mounted on a control panel 46 that is attached to the bench top 23. A conventional fluid pressure guge 47 is also mounted on the control panel 46.

The hydraulic fluid system is illustrated schematically in FIG. wherein it can be seen that the hydraulic pump 38 has a pressure hose line 42 whichis provided with two T-joints 61 and 62. The pump 38 is also equipped with a return hose line 63 having one T-joint 64 connected therein. The first T-joint 61 leads to a conventional bidirectional valve 65 having two pressure outlet hose lines 48 and 49 extending therefrom.

One hose line-48 is connected to the right end of the horizontal hydraulic cylinder 25 while the other hose line 49 is connected to the left end of the cylinder 25. The valve 65 also has a return hose 66 which leads to the T-joint 64 in the main return hose line 65. The right control handle 44, which is best seen in FIGS. 1 and 2, is connected to the valve 65 for directing the pressure fluid from the pump 38 to enter the hose line 48 or to the hose line 49 as is discussed more fully hereinafter.

The second T-joint 62 has a hose line 67 which leads to the pressure gauge 47. This gauge 47 has no return hose line because it merely indicates the pressure of the fluid in the main fluid pressure line 42.

Beyond the T-joint 62, the main fluid pressure line 42 leads to a second bidirectional valve 68 having two pressure outlet, hose lines 50 and 59. One hose line 50 leads to the lower portion of a vertically disposed hydraulic cylinder 51 and the other hose line 59 extends to the upper portion of the cylinder 51. The valve 68 is equipped with the left control handle 45, which is best seen in FIGS. 1 and 2, for selectively directing the pressure fluid through the hose lines 50 and 59 to either end of the cylinder 51, as is discussed more fully hereinafter. The return outlet from the valve 68 is connected directly to the main return hose line 63.

During the operation of the bending machine, the right control handle 44 directs the application of fluid pressure to either the right end of the cylinder 25 or to its left end. Normally, the right handle 44 is in its middle position which, as is indicated in FIG. 2, is its OFF" position signifying that no pressure is applied to the cylinder 25 at this time. When it is desired to pull the two base portions B1 and B2 toward each other, the handle 44 is turned to its PULL. position thereby causing its associated bidirectional valve 65 to conduct the pressure fluid through the hose line 48 leading to the right end of the cylinder 25. The resulting fluid pressure tends to slide the piston 26 further into the cylinder 25which, in turn, tends to pull the base portions B1 and B2 closer together. On the other hand, ifit should be desired to push the two base portions B1 and B2 away from each other, the handle 44 is moved to its PUSH position thus causing its associated valve 65 to conduct the pressure fluid through the hose line 49 leading to the left end of the cylinder 25. The resulting application of fluid pressure tends to push the piston 26 further out of the cylinder 25 and, in turn, tends to push the base sections B1 and B2 further apart. In either case, the magnitude of the fluid pressure is indicated on the dial of pressure gauge 47.

As was stated above, the left control handle 45 controls the second bidirectional valve 68 for applying fluid pressure to either end of a double-acting hydraulic cylinder 51 which is vertically disposed near the left end of the bench top 23 and is securely fastened thereto as is represented, for example, in FIG. 4. This cylinder 51 contains a portion of a piston 52 having its other portion projecting upwardly out of the cylinder 51. The upper end of the piston 52 is equipped with an enlarged support portion 53 which, as is best seen in FIG. 10, has a concave upper surface that is adapted for receiving therein the curved surface of the waveguide 5. In order for the waveguide 5 to be received within the support portion 53, the cylinder 51 must be so mounted upon the bench top 23 as to be in alignment with the two bending heads 1 and 2. In other words, the concavity in the top portion 53 of the piston 52 should be in alignment with the trough areas 9 of the lower clamping portions 3 and 6 of the bending heads 1 and 2.

Normally, the left control handle 45 is in its middle position which, as is shown in FIG. 2, is its HOLD position indicating that the fluid pressure inside the cylinder 51 is static and is neither increasing nor decreasing at this time. When it is necessary to raise the top portion 53 of the piston 52 for the purpose of elevating the associated portion of the waveguide 5, the handle 45 is moved to its UP position. This causes its associated bidirectional valve 68 to conduct the pres-- sure fluid through the hose line 50 leading to the lower portion of the cylinder 51. The resulting increase in fluid pressure causes the piston 52 to slide further upward out of the cylinder 51. On the other hand, when it becomes desirable to lower the top portion 53 of the piston 52, the handle 45 is turned to its DOWN" position thereby causing its valve 68 to conduct the pressure fluid through the hose line 59 extending to the upper portion of the cylinder 51. This change in the application of the fluid pressure forces the piston 52 to slide downward into the cylinder 51. Thus, the cylinder 51 and its piston 52 function in the manner ofajack for elevating, lowering, and supporting the adjacent portion of the waveguide for the purposes that are described hereinafter.

When this bending machine is to be operated for bending a section of rigid circular waveguide, the first step is to openthe upper clamping portions 4 and 7 of the bending heads 1 and 2 and then place the waveguide 5 in the trough areas 9 of the lower clamping portions 3 and 6. The waveguide section 5 is fabricated with a rigid flange 54 at each end thereof, and the second step is to bolt an alignment plate 55 to the flange 54 at the right end of the waveguide 5. One of the purposes of this alignment plate 55 is to reenforce this end of the waveguide 5 so that its circular cross-sectional shape will not become distorted during the bending process. A straight line 58 is inscribed on the right face of the plate 55 and the plate 55 should be so positioned that the line 58 is maintained in a horizontal position.

In order for the first bend to be properly located on the waveguide 5, the right end of the waveguide 5 should project a short distance beyond the right side of the right bending head 2. This desired lateral spacing is obtained by inserting the right end of a spacing stud 56 into a threaded hole in the lower part of the alignment plate 55. The left end of the stud 56 has a hemispherical shape and fits into a hole in the right side of the lower clamping portion 3 of the right bending head 2. The waveguide 5 is then moved axially toward the left until the flange 54 on its right end abuts against the head of the spacing stud 56. The upper clamping portion 4 of the right bending head 2 is now swung downward to engage the upper surface of the waveguide 5. The associated bolts 8 are then swung upward into their respective slots 10 in the portion 4 and their nuts 11 are tightened. This functions to clamp the right end of the waveguide 5 securely in the right bending head 2 so that it is firmly retained therein.

As was stated above, any bends that are made in the waveguide 5 should maintain its circular cross-sectional shape because any distortions thereof would produce objectionable impedance discontinuities which, in turn, would impair the quality of signals transmitted along the waveguide. For this reason, the length of the arc of a bend should be as long as possible. In general, the greater the angle of a bend is, the longer its arc should be.

Accordingly, after the waveguide 5 has been securely clamped-in the right bending head 2, the next step should be to position the left bending head 1 so that the distance, or spacing, between the two heads 1 and 2 will provide the proper arc length for the size of the angle of the particular bend that is to be effected at this time. The desired position of the left bending head 1 can conveniently be obtained by operating the right control handle 44 to either of its PULL or PUSH" positions. For this purpose, a scale 57 is provided on the bench top 23, as is represented in FIG. 2, for indicating distances along the bench top 23 to the left of the center of the right bending head 2.

For example, let it be assumed that the left bending head 1 is in the position where its base portion B1 is located at the position shown in FIG. 2. Let it be further assumed that, for the purpose of making a particular bend, the left base portion B1 should be moved to the position indicated by the numeral 17 on the scale 57. To accomplish this movement, the control handle 44 is moved to its PULL position thereby applying the pressure fluid over the hose line 48 to the right end of the cylinder 25. This forces the piston 26 further into the cylinder 25 thereby drawing the left base portion B1 toward the right and, consequently, decreasing the spacing between the two bending heads 1 and 2. When the left baseportion Bl arrives at the desired position over the scale 57, the control handle 44 is moved to its OFF" position. Similarly, the spacing between the two bending heads 1 and 2 can be increased by moving the control handle 44 to its PUSH position.

After the left bending head 1 has been properly positioned, its upper clamping portion 7 is swung downward and its bolts 8 are swung upward into their slots 10 and the nuts 11 are tightened. Thus, the associated portion of the waveguide 5 is firmly retained by the left bending head 1. The equipment will now be in the condition represented in FIG. 4 wherein the clamping means constituted by the bending heads 1 and 2 are parallelly disposed. It can be seen in FIG. 4 that the top 53 of the piston 52 in the vertically disposed cylinder 51 is not in engagement with the waveguide 5 at this time.

The next step is to adjust the inclinometer 15 to the appropriate angle for the desired bend which is to be effected. This is accomplished by rotating the micrometer head 17 for tilting its associated spirit level 16 to the necessary tilt angle.

The actual bending of the waveguide 5 is accomplished by moving the right control handle 44 to its PUSH position. As was described above, this causes the piston 26 to be pushed further out of the cylinder 25. in other words, this serves to increase the effective length of the extensible portion 26 of the connecting means constituted by the cylinder 25 and its piston 26. In turn, this action functions to spread the base portions B1 and B2 further apart so that the spacing between them is forcibly increased. Since the right base portion B2 cannot be pushed to the right due to the fact that its pivot rod 24 passes through the rails 22, it necessarily follows that the left base portion B1 is pushed toward the left.

This increase in the spacing between the base portions B1 and B2 of the bending heads 1 and 2 must be accommodated in some manner at the upper portions of the bending heads 1 and 2 and this need is met by the forced tilting of the clamping portions 3-4 and 6-7. In other words, the spreading apart of the base portions B 1 and B2 causes the clamping portions 3-4 and 6-7 to tilt simultaneously in opposite directions as is represented in FIG. 5. Due to the fact that these portions of the bending heads 1 and 2 tilt in opposite directions, the intermediate portion of the waveguide 5 which extends between the bending heads 1 and 2 will become bent in an arc as is also illustrated in FIG. 5.

The extent of this bending of the intermediate section of the waveguide 5 can be determined by observing the bubble in the spirit lever 16 of the inclinometer 15. The sliding of this bubble to a level position indicates that the bending process should be stopped. When this condition is obtained, the right control handle 44 is returned to its OFF" position thereby terminating any further tilting action of the bending heads 1 and 2.

The waveguide support jack, which comprises the vertical cylinder 51 and its piston 52, is now activated by turning the left control handle 45 to its UP position. This applies the pressure fluid over the hose line 50 leading to the lower portion of the cylinder 51 thereby forcing the piston 52 to slide further upward out of the cylinder 51 so that the cradle constituted by its concave top portion 53, which is best seen in FIG. 10, will now engage the bottom surface of the adjacent portion of the waveguide 5. This upward movement of the piston 51 is continued thus elevating this portion of the waveguide 5 as is represented in FIG. 6. It can also be seen in FIG. 6 that the left bending head 1 and the left portion of the cylinder 25 are also elevated at this time. This procedure is continued until the bubble in the spirit level 21 on the right bending head 2 slides to its level position. When this occurs, the left control handle is moved to its HOLD position thereby terminating the process of elevating the waveguide 5. If the proper bend has been made, the bubble in the spirit level 16 in the inclinometer should also be in its level position at this time.

If the bubble in the spirit level 16 is not in its level position, its position will indicate either that the bend is not large enough or that the bend is too large. If the bend is not large enough, the bending procedure is continued by moving the right control handle 44 to its PUSH position. On the other hand, if the bend is too large, an unbending procedure should be followed. This is accomplished by first lowering the vertical piston 52 by moving the left control handle 45 to its DOWN" position until the piston 52 returns to its position shown in FIG. 5. The left control handle 45 is then moved to its HOLD position and the right control handle 44 is moved to its PULL" position for pulling the base portions B1 and B2 closer together. In either case, the bending or unbending procedure is stopped when the bubble in the spirit level 16 of the inclinometer 15 slides to its level position. The piston jack 52 is then raised to again elevate the waveguide 5 to its position shown in FIG. 6, and the bubbles in the spirit levels 16 and 20 are again inspected. As was stated above, when both bubbles are in their level positions, the proper bend has been made. Thus, gravity is used as the reference datum for measuring the bends and no physical datum or reference surface is required.

After this first bend has been made correctly, the piston jack 52 is lowered in the manner described above, the nuts 11 are removed, the bolts 8 are swung down, the upper clamping portions 4 and 7 are raised, and the waveguide 5 is removed from the bending machine. Next, the waveguide 5 is reinstalled in the bending machine after first turning the waveguide 5 around so that its end to which the alignment plate 55 is attached will now be at the left as is shown in FIG. 7. The waveguide 5 is now placed in the trough areas 9 of the lower clamping portions 3 and 6 and is rotated therein until the spacing stud 56 is at the top as is also shown in FIG. 7. This rotation of the waveguide 5 should be finely adjusted so that the line 58 on the alignment plate 55 will be horizontal and also so that an imaginary line through the center of the spacing stud 56 and the bottom hole in the alignment plate 55 will be vertical. What is now the right end of the waveguide 5 is so disposed that it projects slightly beyond the right side of the hydraulic pump 38.

After the waveguide 5 has been thus properly positioned, it is securely clamped in the right bending head 2 in the manner described above. The spacing between the base portions B1 and B2 is then adjusted, also in the manner described above, for providing the correct arc length for the size of the angle desired for this second bend. Next, the left bending head 1 is closed and clamped to the waveguide 5 and the inclinometer 15 is adjusted for the desired angle. This second bend is then made by following the procedure described above for spreading the base portions B1 and B2 and tilting the bending heads 1 and 2 as is represented in FIG. 8.

When this second bend has been made correctly, the waveguide 5 should be measured to ascertain whether the two bends result in producing the necessary offset of the ends of the waveguide 5 so that it can accommodate the abovedescribed misalignment between a particular microwave antenna and its associated transmitting and receiving equipment. This can be accomplished by raising the piston jaclk 26 in the manner described above for elevating the left end of the waveguide 5 as is shown in FIG. 9'. The waveguide 5 is thus raised until the bubble in the spirit level 21 on the right bending head 2 is in its level position. A measurement is now made of the distance from the surface of the bench top 23 to the center of the right end of the waveguide 5. This distance is designated in FIG. 9 as being h,. A similar measurement is also made of the distance from the projected surface of the bench top 23 to the center of the left end of the waveguide 5. This second distance is designated in FIG. 9 as being h By subtracting the value obtained for h from the value found for h, the remainder represents the value of the offset of this particular waveguide section 5.

What is claimed is:

1. Apparatus adapted for bending an elongated object,

said apparatus comprising first and second clamping means adapted for securely holding respectively different portions of said object with an intermediate portion of said object disposed between them,

said first and second clamping means each having a base portion, i

said base portions being normally spaced apart by a predetermined length,

tilting means for tilting said first and second clamping means simultaneously in opposite directions whereby said intermediate portion of said object becomes bent,

said tilting means including connecting means for connecting said base portions,

said connecting means having an extensible portion disposed between said base portions,

means for increasing the length of said extensible portion whereby the length of said spacing between said base portions is forcibly increased,

said apparatus further comprising two parallelly disposed rails,

holding means for normally holding a first one of said base portions between a section of said rails,

and pivot means for pivotally attaching the second one of said base portions to a portion of said connecting means for tilting movement on said pivot means.

2. Bending apparatus in accordance with claim 1 wherein said portion of said connecting means is normally disposed between said rails,

and said portion of said connecting means being adapted for sliding movement back and forth between said rails for varying the distance between said first and second base portions.

3. Bending apparatus adapted for bending an elongated object,

said bending apparatus comprising first and second bending heads,

each of said bending heads including first and second clamping means,

each of said clamping means having an area formed in the manner of a trough and adapted for receiving therein a portion of said object and for conforming to the exterior surface thereof,

means for fastening said first and second clamping means of each of said bending heads tightly together after said portions of said object have been received therein whereby said object is firmly held by said first and second bending heads,

each of said bending heads having a body portion,

each of said body portions having a base portion,

said base portions being spaced apart from each other,

means for bending the portion of said object that is intermediate the portions held by said bending heads,

said last-mentioned means including tilting means for tilting said bending heads simultaneously in opposite directions,

said tilting means comprising adjustable means for changing said spacing between said base portions after said first and second clamping means in each of said bending heads have been fastened around portions of said object,

each of said body portions further including a pair of le s, said egs in each of said pairs being in parallel to each other, and said adjustable means being disposed between the legs of each of said pairs and also in parallel to said intermediate portion of said object.

IIK I i 

1. Apparatus adapted for bending an elongated object, said apparatus comprising first and second clamping means adapted for securely holding respectively different portions of said object with an intermediate portion of said object disposed between them, said first and second clamping means each having a base portion, said base portions being normally spaced apart by a predeterMined length, tilting means for tilting said first and second clamping means simultaneously in opposite directions whereby said intermediate portion of said object becomes bent, said tilting means including connecting means for connecting said base portions, said connecting means having an extensible portion disposed between said base portions, means for increasing the length of said extensible portion whereby the length of said spacing between said base portions is forcibly increased, said apparatus further comprising two parallelly disposed rails, holding means for normally holding a first one of said base portions between a section of said rails, and pivot means for pivotally attaching the second one of said base portions to a portion of said connecting means for tilting movement on said pivot means.
 2. Bending apparatus in accordance with claim 1 wherein said portion of said connecting means is normally disposed between said rails, and said portion of said connecting means being adapted for sliding movement back and forth between said rails for varying the distance between said first and second base portions.
 3. Bending apparatus adapted for bending an elongated object, said bending apparatus comprising first and second bending heads, each of said bending heads including first and second clamping means, each of said clamping means having an area formed in the manner of a trough and adapted for receiving therein a portion of said object and for conforming to the exterior surface thereof, means for fastening said first and second clamping means of each of said bending heads tightly together after said portions of said object have been received therein whereby said object is firmly held by said first and second bending heads, each of said bending heads having a body portion, each of said body portions having a base portion, said base portions being spaced apart from each other, means for bending the portion of said object that is intermediate the portions held by said bending heads, said last-mentioned means including tilting means for tilting said bending heads simultaneously in opposite directions, said tilting means comprising adjustable means for changing said spacing between said base portions after said first and second clamping means in each of said bending heads have been fastened around portions of said object, each of said body portions further including a pair of legs, said legs in each of said pairs being in parallel to each other, and said adjustable means being disposed between the legs of each of said pairs and also in parallel to said intermediate portion of said object. 